Surface grinder



1952 A. J. BOWEN 2,603,041

SURFACE GRINDER Filed Sept 27, 1945 v a Sheets-Sheet 1 I40 Eb i INVENTOR.

ALFRED u B0wE/v ATT'V.

.Fufly 1, 1952 A. J. BOWEN 2,593,941

SURFACE GRINDER Filed Sept. 2'7, 1945 8 Sheets-Sheet 2 IN VEN TOR.

ALF/FED JBOWE/V ATTORNEY July 15, 1952 J. BOWEN 8 Shag-Sheet 3 INVENTOR.

HLFEED JTBOWEN BY A TT'OENEY 1952 A. J. BOWEN 9 2,603,041

SURFACE GRINDER Filed Sept. 27, 1945 8 Shegts-Sheet 4 IN VEN TOR.

ALF/PEI) xaowav ATTORNEY y 5 1952 J. BOWEN 2,603,041

SURFACE GRINDER Filed Sept. 27, 1945 8 Sheets-Sheet 5 F Iq. 5.

IN VEN TOR.

ALFRED JBOWEN y 15, 1952 A. J. BOWEN 2,603,041

3U RRRRRRRRRR ER INVENTOR. fiLF/PEDJ BOWEN ATTORNEY A. J. BOWEN SURFACE GRINDER July 15, 1952 8 Sheets-Sheet 7 Filed Sept. 27, 1945 PI======H 5 9 E ill mIEEEEm 4 INVENTOIL ALFRED d. BOWEN A rrr.

July 15, 1952 8 Sheets-Sheet 8 Filed Sept. 27, 1945 I m [M II 9 1 Z 6 1 w 1 7 H WM N 3 7 7 H H w A a 0 AAA 8 8 H 6 mm w M V 1| 5 W a H II m 5 m 9 w 6 6 u w 1 4. k 0 m 2 Z m m I M 4 a M l uvmvrox ALFRED u BOWEN A Tr'k Patented July 15, i952 IIU IT D. STATE.

SURFACE GRIN-DHER 3 Alfred J. Bowen, nn, Wis. 'f I Application September 27,1945,Serial.No..618,il05

Objects of the present invention are to provide be manufactured at low cost, can be easily manu-- ally or mechanically controlled, is simple in construction and has all working parts practically protected from dust, dirt, grinding material and the like. i 1

An object of the present inventionis to provide a design which is rugged and can be manufactured and assembled and made ready for, shipment with the work holding surface in perfect alignment with the grinding surface.

. An object of the present invention is to provide a general. design which can be adapted for differentrequirements. of surface grinding.

An important object of the present invention is to provide a base having mounted thereon a relatively large diameter and hollow post on which to rotatably and slidably mount the, head which carries the face grinding wheel orwheels and whereby after the parts have been assembled into a complete machine, the work holding surface may then be ground true, and whereby this operation may be repeated after an'extended use of the machine so as to again perfectly truethe work holding surface.

Another important object of the present invention is to provide a design wherein theaverage manufacturing machine shop practice may be 13 Claims. (01., 5 1%) followed without scraping or hand fitting, thus to reduce the cost of a machine which is capable of a high degree of accuracy.

-An important object of the present invention is to reduce the moving parts associated with the grinding wheel or wheels to a minimum, attention being called to the fact that there are but twoof such parts, one the fit of the head over the post and the other the bearings on which the shaft of the grinding member is journaled, these being preferably anti-friction bearings and spaced a considerable distance apart thus to doubly insure accuracy of work. I

It will be noted that an important feature of my design is that the device may be provided with one or more rotating work holding platens, and the'grinding element moved from one work holder to the other thus to insure extreme accuracy in grinding and provide time for loading the idle work holding platen while the work on the other platen is being ground. 7 Still another object of the present invention in addition to providing" work holding means on one side of the machine, is to provide a circular work holding table which surroundsthe post and wherein the head-may w equal y seated r n -wh ls whi h: 1193"? around the post and grind the pieces of work successively, thus giving one or more attendants an opportunity toremove and reload the work, or wherein .the grinding wheels may be closely spaced and provide a roughing and finishing p rat n. 1

a In the field of surface grinders forgrinding flat surfaces 'thereare two types, one employing the periphery of the grinding wheelfand the other employingthe flat surface of a cup, ringQdisc or segmental type of wheel. My invention concerns only the later ty'peof grinder. Normal practice is for the work holder to traverse orrotate-the part being f surfaced or ground so these parts follow a pathac'r'os's the wheel which is doing the grinding. I In other cases the grinding wheel. is traversed back and forth across the work to be ground- All such types of machines employ ways uponwhich eitherthe wheel or the Work holder is 'tr'aversedf fIhese waysare subject to wearl'afid are difficult to maintain due to their'location which "s f .o'f necessity. directly exposed to' highly abrasivejdu'st"orcoolant mixture. In addition to these disadvantages they generallyfpresent very expensive manufacturing operations.

1 All of the above disadvantages are eliminated in my construction, and in addition I'present advantages in construction and operation which willhereinafter appear. l f To these'and other useful "ends my invention consists of parts. combinations of parts or'th'eir equivalents and mode ofoperation as hereinafter described and claimed and shown in the accompanying drawings inwhichz- Fig. 1 is a side elevational viewof the simplest formbfmy invention.

Fig.1 2 'is' atop viewof the device as 'shown' in Figural}. igis is aside" elevationalview of a modification..f Fi 4 is a top view of the device as shown in ileureB- 11 1 Fig. 5 is a side. elevational view of a further modification. Fig. 6 is a top view of the device. asillustrated in Figure 5. i Fig. 7 is a sectional view of one form of the controlling-"means which'may be used in the vai' iouise designs." wherein the grinder wheel or wheels'f may bemoved back and forth overthe work-manually "or mechanically and raised and l owerediatithejwill or the operator.

if desired be provide I As thus illustrated it will be seen that applicants invention may be made in various forms each of which have the same fundamentalv characteristics as hereinbefore mentioned.

Referring now to Figures 1, 2 and 7, the base of my device is designated in its-.entir'etyi by1reference character A. The head which carries the threaded sleeve which is held to member 34 by means of bolts 36. It will be noted that the vertical position of member 34 is limited downwardly by means of a flange 31.

Member 34 is slidably keyed into member 3| as at 28. I provide a shaft which extends from the interior of base A to cap 30, the cap resting on shaft 40 by means of a ball bearing 4|, Shaft 40 is screw-threaded as at 2 into member 35,..thu'sit will be seen that by turning shaft'40, head B may be raised and lowered, head B being shown in Figure 7 as near its uppermost position. The head may be temporarily raised by raising shaft 40 and sleeve 34 by means of a hydraulicjack 43 having a tube connection 44 ""which'leads to a control valve (not shown), V whereby the piston of jack 43 may be raised motor and grinding element is designate'd'in'lts entirety by reference character B; a post which acter C comprises atube member l0 having a flange II which rests on'a machined'surface l2 on the top ofmember -A and is securely fastened to this surface H by meansof a number of cap screws l3. Member-l3 is'slidably and'rotatably mountedon-member C. p v

On oneside of member B I mount a bracket J6 in which'is journaled a shaft 140 having mounted on its lowerend a disc ll, the disc being adapted tocarry-agrinding member 18. On the upper end' of theshaftl preferably mount a multiple v belt sheave l4! and on the other side of memberjB I -suitably' mount a motor 19; the shaft 20 of 'whichispreferably provided'with a multiple v belt sheave; and'V belts are provided to form anioperatingconnec'tion between-motor l9 and the ulpper endofthe shaft which carries member l 'I provide a shield 2| adapted to protect or shield" the belts. It will be seenthat grinding surface 18 will be driven'bymotor l9, and that the'upper surfaceof member A in addition to surface lIZhas a machine trued work holding sur faceiz with mean'sjfo'r attaching the work either with clampsor'magnetically'.

I provide a handle23 whereby surface l8 may beimoved back andforth manually over surface 22101- grinding or surfacing whatever parts are placed thereon. I'also provide a collapsible tube 24 which is secured at its top to member B as at 25, its lower end resting'freely on the top of flange, as at '25. This tube may be m-ad'e'of rubberizedfabric material or rubber, or'it may be made in two or more telescoped pieces of metal, and is adapted to shield the surface of post C in whatever vertical position member B may be in. When member B is turned on post C the bottom endof member 24 will slide on flange I l a'sjat'26. Thus any abrasive material or metal'du'st released -while operating the grinder will not "be permitted to contact the machined surface of member C.

It will be understood that I may provide 'mechanical'means for moving grinder surface'r' I8 over the work. One of such means will hereinafter appear, however for small machines I prefer to use handle 23 for the purpose. 7

.I provide means as illustrated in 'Figurep'l'for raising andlowering-head B. Thishead is proand lowered and in turn raise and lower head B.

"Clearly when the pressure is released in jack 43 the weight of member B will cause sleeve 34 to-assume the position shown in Figure 7. It is the intention to permit member B to return freely to its-adjusted position which .is determinedas: follows Shaft 43 is key seated as at 4B, and a worm gear-ll is slidablykeyed to shaft 40 and held between suitable bearings in a bracket 48. I provide a worm pinion 49 which meshes withthe teeth-of gear 41 and is mounted. on a shaft 50 which extends through a bearing member 5| on member A-and has secured on its protruding end a -ha'nd wheel 52. I

Thus it wilLbe-seen by scrutinizing Figures 1 and 7: that the operatorby manipulating wheel 52' may determine the lowest position of head B, which is-the' operating or grinding position as shown in Figure 7. '-By. means ofjack 43 head B may be liftd'tenlporarily high enough so that the grindingx lisc clears the Work as it is returned to the-starti-lig' position and then lowered to its definite adjusted grinding position. In larger machines means areprovided'for moving head B;- back an'd fortlior around the post C hydraulicall-y as-will' hereinafter appear.

' Referring-now to Figures 3, 4 and 9, it may be said that this designis similar to Figures 1 and 2 with the exception of the shape and'construction ofthe work holding means. Inthis design there are provided preferably two revolving work'holding -Itables ='60'-'B0. Each of these tables is mountedgon a post such' 'as-fil which is suitably rotatably m0lll1tefi" ill'-afld-0Ii the base which is designated by reference character BZ. Member has rigidly secured thereto near its lower end a worm gear f63 witha-holding on collar 64. I

' I; provide preferably two driving motors (one not shown) s'uitably secured to member 82, each havinga worm piliionfiiti which meshes with the teeithof the 'associatedgear 63-. Thus it will be 'seen that 'there 'is provided preferably a pair ofrevolving' work holding tables and that these tables may be loaded with work tobe faced alternately. f i "Member Id-maybe *movedto a position-in which it covers about one half of the diameter of oneof the-tables 60, whichis turned slowly by motor-ffififso that the work piece thereon is s'uitably'surfacedg At this timethe other table maybe stcppedfan'd loaded. It will be seen that an ideal condition exists for perfectly surfacing the Work because therejisa multiplicity of. crisscross; 'linesof contact between the I grinding disc andthe"work.'f s] additiohQto the designs already described other "designs 'may'be proinded as in Figures 5. and.6, whereinthe work table extendsfor 3.60 degreesaround the post; In this design I'prefer tosupplyi two grinding members positioned on opposite. sidesof the post and having a: separate motor operatively connected to each grinding disc, so the head may be movedback'and forth or revolved around the post. In" this. design, the base is designated in its entirety by reference character .D,- the head in itsentirety is designated byreference character E and the postxas in the otherfigures. 14 ,3 The advantage of this design is that the grind-, ing.elements.,may Operate continuously when for example two-grindingrheads are used with two attendants for placing theworkpiec'es in position andv removing them after they have been sure faced,; Either, of the operations referred to are possible;; because the head turnson its-post very slowly: It will be understood that thehead may be moved back and forth either' manually. orby hydraulic means as will hereinafter appear. In this design the driving motors F,-F are preferably secured to opposite sides ofmember E from the grinding discs as shown. .In this design shafts are journaled in members Ghaving on their lower ends the discs I! withv the grinding surfaces I8 attached thereto, as in Figures 1, 2, J3: and 4. The upperends o the shafts to which members H are attached are preferably. provided with V, belt pulleys; motors F are provided with V b elt pulleys; and the operatingconnections'between-the motors and their respective shafts are madeby means of V belts. I 1

I;n thi s design and the design shown in Figures 3 andi, means may be provided for turning head B backand forth hydraulically. This means and the-means for raising and lowering the head are shown in detail in Figures 8, 11; and '12- 'I will now describe the controlling mechanism used preferably in-the designs shown in Figures 3-to 6and shown in detail in Figures 8, 11 and 12.

Referring-now to Figures 8, 11.and 12, the base is designated by reference character H, the hollow postis similar to the hollow post in theother design and is designated by reference character .0, the head is similar to that shown in Figures 1 through 6 and is .designated by reference character B. A closure cap for member B is pro-. vided with a downwardly extending sleeve 1|. which is rotatably and slidably mounted in an opening 12 in the top of base H.

MemberC is supported on a machined surface 13. Member II is key seated as at- 14 and ahead I5 having a key I20 which fits into seat I4 is slidably mounted on member II and rotatably secured to base H by bolts'68, the bolts extending through slots 69, so member 15 canact to turn member II back and forth hydraulically as follows:

A hydraulic cylinder I6- is hingedly connected to an anchor bracket 11 as atJS, the cylinder having a piston 19 with apistonrod 80 which protrudes through ansend closure SI of the cylinder, the end being hingedly connected to member.'i5 as at 82. Tubeconnections83 and 84 are made to opposite ends of cylinder 16., These connections lead to a manually controlled valve which is associated with a hydraulic pump (not shown), whereby the operator may, by manipulating; the valve, move head B back-and forth on post 0 as an axis,. thus moving the head hydraulically instead of manually as in Figures 1 and 2.

L I; provide means forraising and lowering head B as follows:- A cap is secured tothe lower end of ;member;1IQhaving a sleeve 88 with a cap '81 secured-to its upper endzi A shaft 88 is slidably mounted in member 85, having a-.packing 89.- The upper. end; of shaft 88 is reduced somewhat as .at 00, its end resting against cap 81. It will be seen that a chamber 03 is provided into which a fitting 94 leads,,having;a tube; 05 which leads to-a control valve, which; is connected to a hy draulic pump,;-so bymanipulating the valve fluid under pressure; ,may be admitted to. and 11 5-, charged fr m. ch mb r .1 an h B mayb raised and lowered. At the lower end of member; 88 I; mount a caplll containing a ballbearingflladaptedto rest on the upper end of a screw -threaded shaft I00. The ball bearin permits shaft;8 8 to-turn freely on the end of the screw-threaded shaft. I provide a bevel gear IOI having secured therein a threaded sleeve; I02. Member IOI rests on a baseextension I03 through aballbearing-IM. g Member I00 is key seated as at I05 and a key I06 ismounted in member I03 so as toengage keyway I05 and preventshaftill'lll from turning. A bracket I01 is-mountedonextension I03 and has rotatably mounted therein a shaft I08, the shaft having secured to-its lower end a bevel pinion I09. Shaftl08 is rotatably mountedin base. H as at I I0, the end of the shaftprotruding through the base and having keyed thereto a hand wheel I I I, the hub of which carries a cali brated discIIZ which may be marked in thousandths ofan inch, as at H3. .A single mark is positioned on baseH for cooperation v with the calibrations H3 sotheioperator mayturn wheel I I I to raise and lower head B one or more thousandths of an inch ata time. p 1 p n Thus clearly the design shown in Figure .8 may be used in: the design shownin Figures 1 and 2, or as stated -.be forev thedesign shown in Figure? maybe used in the machine shown in Figures 3 through 6, the-manner of raising and lowering head ,B being thesame in either design andif desired the hand piece 23 may be used for move ing the discs over the work instead of usingthfi hydraulic means shown in Figures. 11 and12. Whatever manually controlled means areused all of the working mechanism of the control is per fectly protected or enclosed within the'base and post C and with the addition of the telescopic seal 24 around member C my device willretain its working efficiency for an indefinite time. I ,1 It willbe understood that a motor 28.may be mounted on bracket I6 as shown in Fig. 10,;the motor shaft being connected to the. shaft which carries the grinding wheel I8, thus dispensing with the pulleys, belts and shield. Other'changes may. .be'madewithout departing from the spirit and scope of the invention and I do not therefore wishto be limitedto the precise forms of the invention disclosed herein but desire to include' and have'protected by Letters Patent all forms and modifications thereof which come within the scope of-the appended claims. I Having thus shown and described my inventionIcla'im'z e f 1. Asurface grinder of the character'described comprising, a hollow base, the top of said base being machine trued, 'an'opening in the center thereofya circular'in cross section hollow post secured to said base and surrounding said opening, the outer top portion of the base being concentric with" the postand adapted tohold the work to be 'surfac'ed, a head slidably and rotatablymounted onsaid post having a closure 7 at the top thereof, a .disc mounted on the lower end-:of a vertically arranged shaft whichisrotatably mounted on said head, .said' disc being adapted to :carry abrasive material on its. lower side, means mounted on said headadapted to drive said discshaft, means forturning said head continuously on said post asan axis, whereby material placed'on said work holding surface may be successively surfaced by the disc, manuallycontrolled means adapted toslide the head vertically on said post; and a manually adjusted stop adapted to limit the' downward movement of the head.= I

2. A device as recited in claim 1 wherein a collapsible tube is provided surrounding said post, the upper end'of said tube being secured to the bottom of said head with itsbottom end resting freely on the top of said base, whereby the part of said post between the headand base is'protected from contact with loosened abrasive material, metal dust and foreign matter.

3 'A device as recited in claim 1 wherein all of said manually controlled parts are located substantially-within said post and base to thereby prevent contact with loosened materials and dust.

4.A grinding machine of the character described comprising, a hollow base, the top of saidbase being so machine trued and havin an opening in the center thereof, a circular in cross section hollow post secured to said base andsurrounding the opening, a head slidably and rotatably mounted on the post'and' having a closure on the top thereof, a disc rotatably mounted on said head with its lower side adapted to carry abrasive material, means for rotatably driving said disc and means for rotatably driving said head, the remainder of the machine surface of said base being concentric with said post andarranged that the work-tobe surfaced may be secured thereto, said disc being positioned whereby the work may be surfaced as the head travels around the circle, and 'means whereby said head may be raised and lowered on said post.

1 5. In a surface grinden-a base havinga horizontal work holding surface, a vertical column or post fixed toand extending upward fromsaid base'above said'surface, a head member slidably and rotatably mounted on said post by means i of a'bearing comprising an internal cylindrical bearing surface in said head in engagement with an external cylindrical bearing surface on said post, a motor and an oppositely disposed vertical shaft supported on said'head, agrinding wheel mounted on said shaft above said base,-a driving connection between. said motor and said shaft, means including an antifriction thrust bearing supporting .theweight 'ofisaid head and parts-mounted thereon on said postduringrotation of-said head, said last-meansalso including a micrometer screw disposed .on'theaxis of said post-and in operative engagement with" said thrust bearing, and meansin said g-rinderconnected to saidscrew to rotate the same to adjust the elevation of said grinding wheel withrespect towork supported on said base by sliding said head on said post, said head being rotatable to andfro about said post on said thrust bearing in any adjusted position to traverse said grinding wheel over said work.

6. In a surface grinder, a baseya vertical post' fixed to and extending upward from said base, said base having'an arcuate work supporting surface extending around said post as a center for atleast approximately degrees, a head mounted. onsaid post, a grinding wheeland driving means therefor mounted on said head with said wheel above said surface, a bearing included in the means for mounting said head and comprising an axially movable cylindrical internal bearing surface inrsaid head engaging a relatively longer cylindrical external bearing surface on said post, said bearing providing for sliding movement of the head on said'post and independent rotation of said head about said post to move said grinding wheel back and forth in an arcuate path over work supported on said basermechanism operatively connected between said post and head to support the weight of said head during rotation thereof about said post, said mechanism comprising in serial weight supporting relation a thrust bearing, a micrometer screw disposed coaxially with said post, a nut threaded on said screw, and a load sustaining member connected to said nut, and a manually operable device having a sliding connection with said screw to rotate the same in said nut to thereby slide said head on said post and adjust said wheel relative to said work.

7. A surface grinder of the character described, comprising a base, a work holding table rotatablymounted on said base, motor means comnected to said table to rotate the same, a post secured vto said base and extending vertically upward from the level of said table, ahead mounted on said post by means of a'bearing, said bearing comprising an external bearing surface on said post and-an internal bearing-surface in said head in slidable and rotatable 'engagement with said external bearing surface, a shaft rotatably mounted on said head and carrying a grinding wheel above said table, a motor mounted on said head oppositesaid shaft, means connecting said shaft with themotor shaft, said head being rotatable at its bearing on said post to impart a reciprocating movement to "said grinding wheelover said table, mechanism operatively connected between said' head and'post tolsupport said head aga-inst sliding movement on saidpost during'the said movement of said grinding wheel, said mechanism including -a thrust bearing and a lead screw disposed-coaxially with said post, and manually operable means operatively connectedto said lead screw to rotate the same and thereby-slide said-head on said post to regulate the distance between said grinding wheel and said table inaccordance with the thickness of'the work thereon.

8. In a surface grinder, a base, a horizontal work holding surface on said base, a vertical column fixed vto and extending upward from said base above. said surface, a head slidably-androtatably mounted on said column, a radial-face grinding wheel mounted on said head and adaptedto be traversed back and forth in grinding'relation to a work" piece supported on said surfaceby rotation'of said head-on said column, elements including a thrust bearing, a screw threaded shaftand a nut threadedthereon operatively disposed on'the axis of said column and supporting the weight of said-head during the :said rotation thereof, a support on said columnrengaged. bycne of said-elements and sustainingisaid weight, a member'rotatably mounted on the axis'of said column, a sliding' but nonrotative connection between said' member and saidsshdftand me'ansoperatively connected to said member to rotate the same to rotate said shaft in said nutito thereby raise'or lower said wheel and driving means therefor,-

grinding wheel relative to said work piece by sliding said head onsaid column.

i .9. ,In asurface grinder, abase having .awork supporting surface, a vertical column fixed tov said base and extending upward from said base above said surface, a head carrying a grinding bearin means slidably and rotatably mounting said head on said column, means including a thrust bearing-and a pairof inter-engaging threaded imembers disposed on the axis'of said column and 1 supporting the weight of said-head duri'ngslidand rotary movement thereof on said column, means connected to one of said members for rotating the same relative to the other said Imember-to adjust said grinding wheel rel'ativeto a work piece on said surface by sliding said head on said column, and means for rotating saidhead about said column on said thrust bearing to traverse the grinding wheel in an arcuate path over said work piece to grind the same,;.said last means comprising hydraulic 1mechanismi ineluding a cylinder and piston operativelyp'onnected between said head and said base.

10. In a surface grinder, a vertical column, a

supporting head for a grinding wheel mounted on said column, the mounting comprising bearing means providing for sliding movement of the head on said column and rotation of the head about the colunm as an axis, a radial face grinding wheel and driving means therefor mounted on said head, a screw threaded member having a support on said column, said member being vertically movable relative to said support, cooperating elements including said member, a second screw threaded member in threaded engagement therewith and a thrust bearing supporting said head on said column during rotation of said head about said column, said threaded members and said thrust bearing being coaxial with said column, means connected to one of said screw threaded members for rotating the same relative to the other said member to adjust said grinding wheel relative to a work piece by sliding said head on said column, said first member resting on said support during such adjustment and said head being rotatable at the same time about said column on said thrust bearing to traverse the grinding wheel in an arcuate path over said work piece to grind same, and means for-lifting said first member off said support and returning it thereto to raise and lower said grinding wheel relative to said work piece without disturbing the adjustment efiected by means of said members, said lifting means comprising a jack disposed beneath said column, said jack including a vertically movable member adapted to operatively engage one of said supporting elements and thereby raise and lower said grinding wheel as set forth.

11. In a surface grinder, a base having a hori- V at a fixed distance from said post and having a l driven connection with said motor, a radial face "grinding wheel mounted on said shaft and movable toand fro in an arc with its radial'face :parallel to said horizontal surface and in contact with'the top of work supported thereon, said head rotating about said post during such movement, mechanism operatively connected between said base and'head and supporting the weight of'said head'and p'artsmounted thereon during said movement of said grinding wheel, said mechanism comprising in serial relation a thrust face of said grinding wheel and said Work by the weight of said-headand parts mounted thereon.

12. Ina surface grinder, a. basehaving a horizontal work supporting surface, a vertical column *fixed to. said base and extending upward from said surface, a head mounted' 'on said column, the mounting-; means comprising 'interengaging bearing surfaces carried bysaid head and colnmn, respectively, and providing for simultaneoussliding of the head on said'columnand rotation of said head on said column, a vertical shaft rotatably mounted on said head at one side of said column, a motor mounted on said head on the opposite side of said column, a driving connection between said motor and said shaft, a grinding wheel mounted on said shaft and having a grinding face above and parallel to said work supporting surface, said grinding wheel being movable in an arc over a work piece on said supporting surface by rotation of said head on said column with said grinding face in grinding engagement with the upper surface of said work piece, a thrust bearing disposed on the axis of said column and including a part rotating with said head, means including said thrust bearing supporting the weight of said head on said column during said rotation of said head and the said arcuate movement of the said grinding wheel, and mechanism connected with said thrustbearing and operative to lower said head by sliding movement thereof on said column to thereby utilize a portion of said weight to effect pressure of the grinding wheel against said work, said mechanism being included with said thrust bearing as part of said weight supporting means and comprising a screw threaded shaft and a nut in threaded engagement therewith, said screw threaded shaft and nut being disposed with said thrust bearing on the axis of said column.

13. In a surface grinder, a base having a horizontal work supporting surface, a vertical column fixed to said base and extending upward from said surface, a head mounted on said column, the mounting means comprising interengaging bearing surfaces carriedby said head and column, respectively, and providing for simultaneous sliding of the head on said column and rotation of said head on said column, a vertical shaft rotatably mounted on said head at one side of said column, a motor mounted on said head on the opposite side of said column, a driving connection between said motor and said shaft, a grinding wheel mounted on said shaft and having a grinding face above and parallel to said work supporting surface, means for adjusting the vertical position of said head on said column to bring the grinding face of said grinding wheel into engagement with they top of a work piece on said work supporting sur- I Number- 11 face while permitting rotation of saidv headto traverserthe grinding wheel backand forth with itsv'grinding face in contact withv said twork piece, said meanscomprising a supporton said column andelements' operatively disposed in series on the axis'of said column between saidsupport-and said head, said elements comprising a threaded shaft, a nut in threaded engagement with :said shaft; and a thrust bearingvv engaged; by said shaft, said thrustbearing including apart rtating' with said head, and mechanism having ail-operative connection to one of said threaded members'to rotate the samerelative to theother said threaded member :during rotation of 1 said head-and grinding wheel to adjust the position of-"said head asset forth and regulate thepdepth ofthe cut;

' 1,182,861 Sbencer 11 :May s, 1916 Number I Number 1 Name Date; PorterJ Dec;l23,i1919 Hanson vOct..4, .1921 Oubridge Apr. 5, 1927 Schatz Mar. 26, 11929 Ripley, June 11,1929 Hawes 1 Mar. 6, 1934 Gideon May 20, 1941 Ahnert Oct. 21, 1941 Musselman Oct. 28'; 1941 Indge May 26, 1942 Schlichter: Sept. 29, 1942 Scrivener1 1 Nov. 2, 1943 Sjostrand May.2, 1944 Ford Julyll, 1944 Wessman .4, Nov. .14, .1944 Rosmait 1 Jam-21,1947 Fielding 1 Feb; 10; 1948 FOREIGN PATENTS Country Y Date 4 Great Britain July 21, 1927 Germany Oct. 19, 1920 

